Insights

A ROAS of 4.0: has your AI report earned its budget recommendation?

Check the evidence between attributed purchases, additional revenue and the return expected from a larger advertising budget.

The key idea

An AI-written report can calculate return on ad spend correctly and still recommend a budget increase for the wrong reason. Attributed ROAS alone does not establish that advertising created additional revenue. Nor does it establish what another unit of spending would produce.

A hand lifts a transparent sheet with turquoise blocks above a sheet with navy blocks on an ivory desk, with a laptop behind.

For a marketing leader or agency reporting owner, the useful review question is therefore specific: what evidence supports the move from attributed purchases to additional sales, and from those sales to a larger budget? AI can prepare traceable commentary. The person approving the decision must check whether its conclusion fits the evidence.

What the ROAS number actually says

ROAS divides a conversion value by advertising spend. With attributed ROAS, the numerator is the value assigned to advertising under the source system’s tracking and attribution rules. Those rules help describe credited performance; they do not show which purchases would have happened anyway.

In Google’s user-based Conversion Lift, incremental ROAS divides the estimated additional conversion value caused by the specified advertising by ad spend. It needs a credible counterfactual: an estimate of what would have happened without that advertising. A dashboard total cannot supply that comparison simply because a language model explains it fluently.

Preserve the numerator’s definition. A configured purchase value need not equal collected revenue, and neither attributed nor incremental ROAS is a measure of profit. Margins and other costs remain relevant to a budget decision.

A correct calculation with an unsupported conclusion

Consider one hypothetical retailer, not a client result. Its campaign dashboard shows THB 100,000 of advertising spend and THB 400,000 in attributed purchase value for one month. A promotion also ran. No causal study has been supplied.

The calculation is straightforward: THB 400,000 ÷ THB 100,000 = 4.0 attributed ROAS. But the proposed narrative, “Advertising generated THB 400,000 in additional revenue, so increase the budget,” adds two conclusions the inputs do not establish.

A defensible replacement is: “For the reported month, the campaign dashboard attributed THB 400,000 in purchase value to advertising on THB 100,000 of spend, giving an attributed ROAS of 4.0. The supplied evidence does not estimate the incremental effect.” In a live report, replace “the reported month” with the actual reporting dates.

The promotion is a possibility to investigate, not a proven explanation of the purchases. The reviewer should also resist presenting 4.0 as 400% profit. Correct division does not resolve either the causal question or the business’s economics.

Identify the kind of evidence behind the sentence

Start with what the source actually measures. A before-and-after increase describes a change. Attribution assigns credit. Neither alone establishes a valid no-ad comparison. An experimental estimate and an observational causal-model estimate make different claims and need different checks.

A controlled experiment compares treatment and control groups under a suitable design. Google’s Conversion Lift offers user-based and geographic approaches, but is not available to every account. Qualified measurement design matters: a credible study is more than subtracting two raw group totals, and a suitable test need not be a native Google study.

Marketing mix modeling can also estimate causal effects from observational data under assumptions. It must address confounding: another factor affecting both media decisions and sales. Promotions or seasonal demand may warrant consideration, depending on the business and model. A language model writing commentary is not itself such a causal model.

Google’s Meridian guidance also explains why models with good predictive performance can produce different causal ROI estimates. Ask for the causal assumptions, not merely a chart showing that predictions track sales.

A larger budget asks a different question

Even credible evidence about a past campaign does not automatically justify carrying its average return into a larger budget. The practical issue is the return on the extra spending. Reaching additional customers may differ from reaching those already covered; the report needs evidence for its proposed spending level.

Meridian distinguishes historical ROI from marginal ROI, the return on a small spending increase. Its response curves model outcomes across spending levels, allowing larger budget scenarios to be compared. Estimates beyond observed spending carry greater extrapolation risk. These causal-model measures are distinct from platform-attributed ROAS.

Without that evidence, a business may still choose a bounded increase under uncertainty. The report should identify the decision owner, the assumption being made and what evidence will inform the next review. Missing measurement does not require every decision to stop, but it does limit the certainty of the recommendation.

Copy these fields into the reporting brief

MindVerve proposes reviewing one record per material claim. First highlight consequential language such as “caused,” “generated additional revenue” or “will increase.” Then classify its evidence and retain the following fields beside the original sentence:

  1. Claim and decision: the exact sentence, its evidence type and the decision it supports.
  2. Metric and source: original name, definition, report reference and retrieval date.
  3. Scope: reporting dates, campaigns, audience and measured outcome.
  4. Method and comparison: attribution rules, experimental design or causal-model counterfactual.
  5. Limits: uncertainty intervals where supplied, assumptions and missing evidence.
  6. Approved wording and follow-up: reviewer, budget owner and next action.

AI can draft this record and flag gaps. A reviewer must open the source, check its meaning and approve the consequential conclusion. Rewrite the claim only as strongly as the evidence permits; request missing material when stronger wording matters. A prompt or checklist cannot guarantee that this judgment is correct.

Test the reporting pilot before relying on its recommendations

Use three proposed acceptance checks with representative inputs. These are tests to run, not reported test results.

  1. Attributed-only input: the output preserves the attributed label and does not invent incremental revenue.
  2. Inconclusive study: the output retains the supplied uncertainty and does not turn an inconclusive estimate into certainty of no effect.
  3. Causal-model estimate: the output preserves scope and assumptions and does not describe observational modeling as an experiment.

Track corrections to unsupported claims, the proportion of material claims traceable to evidence and total review effort. Include source-checking time: polished commentary that creates more verification work may not meet the pilot’s purpose.

MindVerve’s reporting automation work maps inputs, outputs, owners, calculations, checks, review points and failure rules. AI Workflow Launch implements one agreed workflow with representative and exception tests, documentation, training and handover. Access, configuration, licences or API use, extra integrations and maintenance require an agreed scope; causal-model deployment and experiment setup are not implied.

Official sources

Google Ads · User-based Conversion Lift metricsGoogle Ads · About Conversion LiftGoogle Meridian · Causal inference (2026-09-01)Google Meridian · ROI, marginal ROI and response curves (2026-05-15)

MindVerve

Marketing automation

Bring one anonymised report, its source definitions and the decision it should support to discuss a scoped reporting pilot. That gives the discussion a concrete claim to examine and a human owner for the eventual budget decision.

Discuss a reporting pilotRead the guide · AI Workflow Launch

Continue exploring

AI in marketing analyticsWhy Google Ads and GA4 conversions differAutomating marketing reports with CodexMarketing automation servicesAI ads: more clicks, but more customers?